Application

How to Read the Accuracy Index of MEMS Inertial Devices

High Performance North Seeking MEMS Gyroscope

Here we take the representative ERICCO’s MEMS gyroscope ER-MG2-100 as an example to interpret the parameters.

Click the attachment at the end of the article to download the Data Sheet for this product.

Dynamic Range: This dynamic range refers to the range, which corresponds to different gyro ranges and is suitable for different application scenarios. The absolute error of the sub-model with a large range will also be amplified (because the relative accuracy of a sensor is generally unchanged). The range of ER-MG2-100 is 100°/s, and the ranges of ER-MG2-300/400 of the same series are 300°/s and 400°/s respectively. Therefore, when selecting the sensor, choose the one that is just enough according to the actual needs.

Scale factor: This refers to the design value (nominal value, rated value) of the scale factor (scale factor) of the inertial device, which is similar to the reciprocal of the pulse equivalent in traditional optical gyroscopes. It tells the user how to convert the digital quantity output by the device into the gyro angular velocity. Its unit LSB/°/sec should be written more strictly as LSB/(°/sec), where LSB refers to the least significant bit of the sensor output digital quantity (Least Significant Bit). Sub-models with different ranges of course correspond to different scale factors, generally divided into two modes: low resolution (16-bit) and high resolution (24-bit). resolution mode.

MEMS Gyro

Bias Repeatability: Similar to the Repeatability of the previous scale factor. The specific value of 0.1°/h is very small, which shows that the long-term stability and repeatability of this gyro bias are relatively good. On the contrary, the long-term stability and repeatability of the gyro bias are poor. When used for GNSS/INS integrated navigation, this kind of slowly changing or constant bias error component in a single use requires an integrated navigation algorithm for online estimation and compensation. Reduce the impact on system performance.

Bias Instability: This is the important accuracy metric we really need to care about. The zero-bias instability of a single power-on, the 0.02°/h given here is very small. Typical tactical level.

Angular Random Walk: Angular random walk (ARW), which is actually the angular rate white noise output by the gyro. Value <0.005°/√h.

Error over Temperature: The full temperature bias error of the gyro refers to the change in the zero bias of the gyro relative to the room temperature zero bias within its rated operating temperature range.

Sensor Resonant Frequency: Many people do not understand this parameter. It refers to the resonant frequency of the micro-silicon mechanical structure inside the gyroscope. It is better to have a higher frequency, so that the internal sensing structure is not easily disturbed by sound waves in the environment (such as sirens) or sharp impacts.

Output Noise: Gyro output noise±0.01/±0.003 deg/s, this indicator is actually repeated with the previous Angular Random Walk (ARW), just that the RMS value of the noise amplitude is given here, not the power spectral density of the noise, the two can be converted to each other.

RMS=ARW*sqrt (BW)

3dB Bandwidth: The bandwidth of the gyro, 50Hz is enough for most applications. In addition, when we refer to the RMS amplitude of the sensor noise, the corresponding bandwidth should be given at the same time, otherwise the RMS amplitude is meaningless.

 

Share article
Previous News
Space Made UAV Fire Extinguishing System Unveiled
Next News
The Shenzhou Mission Was a Complete Success
Menu